1. Field of Invention
This invention relates generally to circuits for facilitating magnetic reading, writing and erasing. More specifically, this invention relates to providing bias and erase signals which are independent of power supply fluctuations.
2. Description of the Prior Art
Representative of the closest known prior art patents are U.S. Pat. Nos. 2,810,073; 3,038,036; 3,201,713; 3,305,795; 3,346,821; 3,354,270; and 3,424,871. These patents were developed during a novelty search. Of these U.S. Pat. Nos. 2,810,073 and 3,354,270 are considered the closest in that sinusoidal outputs are generated. The first basically deals with output amplitude stabilization which is accomplished through regulating the power supply voltage. With the subject invention, the circuit is made insensitive to the supply voltage. The second discloses a push/pull circuit configuration rather than a negative resistance oscillator. In addition, the IBM Model 271 Recorder utilizes a soundhead to form a part of an LC tank circuit, but a separate stable reference voltage is not used.
When a low distortion sinusoidal bias and erase oscillator is to be provided for use in portable or miniature battery operated magnetic media recorders, a number of problems are encountered. In addition to low distortion, the amplitude and frequency of the oscillator must be insensitive to battery voltage fluctuations, the required battery drain must be low, and the number of circuit components must be low and small in size. These problems are overcome with the oscillator circuit of this invention.